Learning Table Tennis with a robot

Table Tennis Thoughts

One of our readers, Gary Buck has put together his thoughts on Training with a robot. It would be interesting to hear others' thoughts on the subject.

We will be releasing a video shortly on how to develop your training which also look at some of these areas that Gary is talking about.

Gary Buck

The Basic Idea

There are lots of excellent books, as well as online coaching resources, to teach table tennis skills. Given that the game of table tennis requires two players (at least) the vast majority of these resources assume that the learner has a training partner, and the two partners work together to develop their skills. However, not everyone does have a training partner. The alternative is to use a table tennis robot. This is my situation. However, despite the availability of quite excellent table tennis robots, there are very few resources explaining how to use these to develop a full set of table tennis skills. This article is my attempt to remedy that. It is my attempt to lay out a training plan to develop competent table tennis skills based on practice with a robot.

Of course, it is also a good idea to have your strokes reviewed by an experienced coach. No doubt a live coach is preferable, if available, but alternatively, online coaches are available. You simply take videos of your strokes, and have these reviewed by a coach, over the internet. There is a range of online courses available. I have become a member of the Ping Skills online training site (https://www.pingskills.com), which provides both instructional videos, and video review of my strokes. This is very helpful to me, since it reassures me that my strokes are reasonably correct. Others will not doubt prefer other resources, but the important thing when learning on one’s own is to get some expert review.

I have organized this training course as a steady progression through a number of distinct stages. The idea of different stages of practice comes from Larry Hodges’ article published on his blog in November 2010 (http://www.tabletenniscoaching.com/node/25). Mr Hodges describes six stages of practice, from the simple to the more complex. These are intended to take the player from learning the basic strokes, through developing footwork to randomized drills intended to replicate realistic match play. Mr Hodges’ article does not provide a detailed program for developing the necessary skills, but rather an overview of the principles. He also assumes the availability of a practice partner. In this training plan, I have modified his six stages somewhat, based on my own learning experience, and attempted to adapt his overall idea to my own situation. Thus, I have designed this plan with the exclusive use of a robot, and added specific details of the drills that can be used. (I hope Mr Hodges will not feel I have violated his ideas too much.)

I should stress that I have no experience as a coach. This training plan represents not only me learning to play table tennis, but also me learning how to develop table tennis skills.

Regarding the Robot

There are quite a number of different robots on the market, and these vary considerably in what they can and cannot do. The robot I am using is the Butterfly Amicus Professional. This is a very capable robot, but with very little support on how to effectively use the robot to develop table tennis skills. This lack of support is the main reason I started to develop my own training plan. I believe that this robot is capable of carrying out all the following drills.

Other robots may not perform all the functions described in this plan. Some robots will only allow the most basic functions, whereas others will require some creative use to perform some of the drills described. Users of other robots will have to do the best they can.

It is important to realize that table tennis robots are not precision instruments. (Come to think of it, neither are practice partners.) Although the makers might suggest that robots can send the same ball repeatedly to the same place, this does not always happen. There is always some variation between the shots, even if they are intended too be exactly the same. This happens because of the basic robot design, which uses one or more spinning wheels to throw out the balls as they are pushed up a tube. The mechanism is not so precise. And also, balls are not all perfectly round, especially cheap practice balls. (The better the quality of the balls, the more consistent the shots, I am told.) What this means is that there will always be some degree of variation in the shots from the robot.

Placement of shots will usually vary from the target by just a couple of inches, but occasionally by far more. Some people may consider that a good thing. Good or not, you should use this to help you develop your skills. Make a habit of watching every ball, and moving to the ball, even if it is just a little. And always be aware that even though you know where the next shot should land, it may be off target. Even with the most basic drills, never assume that the ball will land where it should. You should always be ready to adjust.

In the later stages of the program, we introduce random placement and random shots. Mr Hodges suggests that this is a very important aspect of developing table tennis skills, and that failure to train with random drills is one of the most important reasons why many intermediate players don’t progress to an advanced level.

The Practice Sessions

It is assumed that learners will allocate some time on a regular basis to practice. Obviously, the more time invested, the faster the progress. I tend to spent about two hours per session. Each practice session should follow a regular format.

Begin each session with some simple stretches of the muscles to be used.

After this, do some simple warm ups. Start with practicing basic strokes; say a few minutes minutes forehand drives and then a few minutes backhand drives. Then a few minutes of basic footwork drills to increase the heart rate.

Each session should include service practice. Get a bucket of balls and work on your serves. This may be at the start of the session, at the end of the session, or interspersed through the session. But all coaches seem to agree that serves are one of the most under-practiced aspects of the game, and yet one of the best ways to improve. Thus, regular service practice is important to becoming a better table tennis player.

The bulk of the training session is then spent on the drills listed below.

There are six stages of practice. Although these do get progressively harder, get do not comprise a strict serial progression, where you move rigidly from one stage to the next, but rather you will cycle through the stages as new skills are learned. You may, for example, be working on Stage Two skills with one stroke, and Stage One skills with a different stroke. The ideal is to find a balance between working on consistency with fairly easy drills, and then pushing your limits by increasing the difficulty. As shots become more difficult, you will reach the limit of your ability, and the shot will tend to break down. When this happens, ease back to the point where you can be consistent again.

In all these drills, it is important to be relaxed. This applies to everything: how you hold your bat, your arm movement, your body position, your stance, your footwork, etc. You may be tense as you struggle to master a new skill, but work on it until it is easy and relaxed.

The Quality of Practice

The purpose of practice, obviously, is to get better. Practice is, essentially, a brain-training course. This takes place through two related processing mechanisms:

Servomechanism, which is any process that automatically uses feedback to self correct; in the case of table tennis skills, the brain unconsciously uses feedback to self-correct and improve performance—this includes footwork, stroke mechanics, timing, racket angle, ball contact, etc. These all improve without the player being consciously aware of the subtle adaptations being made.

Automatization; the brain has two ways to perform skills, conscious control, where the conscious mind makes the decisions, and automatic control, where the skills are carried out automatically, outside conscious control. Efficient performance of any complex skill required automatic control of that skill. Since table tennis is such a fast sport—there’s little time to think—responses must be completely automatic, and the purpose of practice is to automate performance.

You could say that we learn through the servomechanism processes, and we play through the automatic processes.

It seems obvious that the more you practice the faster you will improve. In fact there is a popular notion that you need to practice 10,000 hours to become an expert in any skill. The is a misunderstanding of the original research: the 10,000 hours was the average number of hours that a group of high-level experts had practiced—some had done far more and some far less. What researchers currently believe is that while lots of practice is important, it is the quality of the practice that is most important. Good practice is referred to as “deliberate practice”, and has four important qualities. These are:

You must be motivated, focus on the task, and make an effort to improve your performance.

The task should be within your ability level, and doable, with effort and concentration.

You should get immediately feedback about your performance.

You should keep repeating the same or similar tasks.

It seems obvious to me that table tennis drills can easily meet these requirements. You should try to do every shot correctly, and accurately to the best of your ability—including footwork, stroke mechanics, placement, etc. You should set yourself attainable targets a little above your current ability level, and work to attain them. And you should continually note your success, and keep trying to do better. And obviously, keep doing this again and again. In other words, no sloppy practice, but everything always done to the best of your ability, again and again.

There is an old saying that “practice makes perfect.” This is only partly true. Better to think that practice makes permanent. If you practice doing things perfectly, then practice does make perfect, but otherwise, it does not.

Stage One: Stroke Basics

The idea here is to learn each of the basic strokes, and repeat them until you can perform them correctly and consistently. Start with the most basic strokes:

forehand drive — against a little topspin

backhand drive — against a little topspin

forehand push — against a little backspin

backhand push — against a little backspin

forehand block — against a little topspin, perhaps a little faster than the drive

backhand block — against a little topspin, perhaps a little faster than the drive

Robot Drills:

Set the robot to deliver one ball repeatedly to the same place. Focus on correct stroke mechanics, and repeat the stoke until you can consistently return the ball with a correct stroke. Start slowly, say 20 - 25 balls per minute, or whatever is comfortable. As the stroke improves increase the frequency. For a beginning club player, 40 balls per minute seems about real match speed, so this should be a good initial target.

Choose the appropriate delivery and speed for each stoke. For the forehand and backhand drives, a fairly long placement, say a foot from the end of the table, with a little topspin is probably ideal. Start slowly, and focus on correct stroke mechanics.

Once you can return twenty to fifty balls consecutively, with good stroke mechanics, then slowly increase the speed, or the topspin, or the frequency, as you gain more control. If you increase too quickly, back off a little. Don’t worry too much about placement of the shots at first, but as you gain more confidence, start to aim for the forehand and backhand corners.

More advanced strokes:

Later, you will want to add other strokes, as well as different spin. The most common might be:

forehand flicks (flips)

backhand flicks (flips)

forehand loop against topspin

backhand loop against topspin

forehand loop against backspin

backhand loop against backspin

forehand chop

backhand chop

back-hand blocks; against all types of spin: then add some variation such as punch blocks, chop blocks, sidespin blocks

forehand block, against all types of shots

Try different variations of these strokes. Also practice these against different amounts of spin: heavy spin, light spin, no spin, left or right sidespin, etc. Then, as you improve, try to generate different amounts of spin yourself, as well as different speeds—fast returns, slow returns, etc. Variation is important.

The principle is always the same: start slow and easy, with a focus on stroke mechanics, then slowly make the shots more challenging, as you gain more control.

Try to simulate double-bounce serves, and practice long pushes, short pushes, and flicks.

Stage Two: Move to Strokes

Once you can make the strokes correctly and consistently, it is time to add footwork. This means moving to the ball to make the same strokes you have practiced in Stage One. The focus initially is on simple, one-step footwork, using correct shuffle steps. As the footwork patterns become ingrained, then begin to focus on the stroke again. It is important that you move into position first, then play the stroke.

Then, once you can move to the ball correctly, and make the stroke successfully, then think about placement. Aim for the two corners, down the line and cross court, as well as the center table where you expect to find the opponents elbow (the cross-over point between backhand and forehand).

Initially, you will probably find that you need to turn down the frequency to about 20 balls per minute. Increase the frequency as you improve.

Robot Drills:

Set the robot to deliver two balls consistently to two different points on the table. Repeat the drill until mastery.

Shuffle step drills: These drill the most basic side to side footwork patterns. Set the robot to deliver a ball to within a foot from the end of the table, with slight topspin.

In and Out drills: Practice stepping in with the racket-side leg under the table (right leg for right-handed players), to take short balls over the table, then step out back to the neutral ‘ready position.’ Repeat.

Practice these basic footwork patterns until you can perform them automatically, in a relaxed, easy manner.

Stage Three: Combining Strokes and Complex Movements

Now we add more stroke variation to more complex footwork, as we practice moving around the table more.

Robot Drills:

Three-Ball Drills: delivery with some topspin; return with drive, block or loop

At some point, introduce the crossover step when you move quickly from wide left to wide right to execute a wide FH. Integrate this into your practice.

Four-ball drills: delivery with some topspin; return with drive, block or loop

BH from left, FH from mid, BH from left, FH from right.

FH from right, BH from mid, FH from right, BH from left

BH from left, BH or FH from mid, FH from right, BH or FH from mid

FH from right, BH or FH from mid, BH from left, BH or FH from mid

Step in drills: step in with right leg under the table to take a short ball that has slight backspin (to simulate double-bounce serve, or short push), return with push or flick. The long ball should have topspin or backspin; return topspin with drive, loop or block, backspin with loop.

BH from short left, BH from long left

BH from short left, FH from long right

FH from short right, FH from long right

FH from short right, BH from long left

Variation of spin and speed:

Start to use various types of spin—topspin, backspin, sidespin, and no spin to these drills; also vary the amount of spin. Use a variety of different shots. Mix in drives, with blocks and loops; push long, or short, or flip short balls. Find as many variations as possible. Once you can complete a drill successfully, change the parameters: different spin, different placement, different speed. Try to place shots in the corners, cross court or down the line.

Stage Four: Mixing It All Up

In Stage One we are repeating the same shot many times in order to get the basic stroke action completely automated. In Stages Two and Three we are repeating a sequence of shots, but always the same shots. This provides some variation moving between shots, but still allows us to work repeatedly to improve our shots. We improve by repetition.

However, in match situations, we do not get to repeat the same shot, or the same sequence of shots. Rather every shot is unique, and is played just once. Our eventual aim is to learn how to play each shot correctly, first time, every time. In Stage Four, we work towards playing each shot once, and getting it right first time. We use the same drills as in Stage Three, but we mix different shots together, such that we do not repeat the same sequence of shots. There are two ways we can do that, firstly by varying our return, and secondly, by varying the balls we receive. We can also set up entirely new drills to replicate match situations.

Varying the Return:

Still using the same drills from Stage Three, we can mix things up by varying our return. We simply respond to each shot in a variety of different ways. For example, if there is a FH topspin in a drill, we do the drill in the normal manner, but the first time we might respond to that FH topspin with a standard drive, the next time we might respond with a fast loop, then a spinny loop, and then a block. Or if we have a short ball, we might return that ball alternately with a long push, a short push, and then a flick. Every time we respond to a particular ball, we switch from one stroke to another.

Varying the Receives

By making only slight modifications to the Stage Three drills, we can vary the shots within the drills. We simply modify some of the shots we receive from the robot by changing the spin, speed or placement. For example, if there are two FH topspins as part of a sequence, we can replace one with backspin. This means we can then practice a FH loop, against topspin, followed immediately with a FH loop against backspin. Switching from looping backspin to looping topspin is a particularly good exercise. Or we can make one shot very spinny, and the next time we receive it, with no spin. Be creative and find ways to challenge yourself.

Simulating Match Play:

Perhaps the best way to mix things up is to develop drills based on real match situations. Be creative here, and start to think about how you like to play your game. Practice setting up your favorite attacking shots. Here are some possible examples.

Loop Drill #1

Receive serve to short left, return with BH long push

Receive long backspin to left, return with BH loop

Receive long topspin to right, return with FH loop

Loop Drill #2

Receive serve to short right, return with FH long push

Receive long backspin to right, return with FH loop

Receive long topspin to left, return with BH loop

Top Spin Serve #1

Receive short top spin serve to left, return with BH flick

Receive long topspin drive to left, return with BH drive

Receive very fast topspin drive to right, return with FH block

Top Spin Serve #2

Receive short top spin serve to right, return with FH flick

Receive long topspin drive to right, return with FH drive

Receive very fast topspin drive to left, return with BH block

Long Pendulum Serve

Receive long sidespin (with or without topspin or backspin) serve to left, return with BH drive

Receive long topspin to right, return with FH loop

Receive fast skinny loop to right, return with FH countertop.

Be creative, and find ways to mix up your shots. If you find weaknesses, then take those shots, or those combinations, and go back to earlier stages and work on them until you can perform them correctly, at will.

As noted earlier, you should be practicing your serves as well as doing these drills. Start thinking about how you serves integrate into your game. Although is it hard to serve and then get the robot to send you a service return (getting the timing right is difficult), nevertheless, you should be thinking about what returns are likely from our favorite serves, and practice hitting against those. Or alternatively, as you practice you will start to develop particularly strong shots. You can then practice the serves that are likely to give you a return that you can attack with your strong shots.

Stage Five: Add Randomization

In Stage Five, the key is on the decision making. All of the drills so far have been predictable, in the sense that we have decided which shots we will receive and where they will come. In reality, matches are not like that. We now need to add randomization to our game. This is very easy to set up with a robot, but the robot has significant differences from a real player, and we need to be aware of those differences to find creative ways to use our robot effectively.

The problem is that in a real game, we receive a wide variety of clues that we do not get from a robot. Firstly, we see the player, where they are standing, where they are facing, and where they are looking at. We can watch the action of their bat and see where they are aiming. We get none of that from a robot, it simply spews out a ball, with virtually no hint about where the ball will go, or what sort of speed or spin is on the ball. Furthermore, most players stand back from the table, and this gives us more time to watch the ball, and respond, whereas most robots stand on the end of the table, and give us much less time to respond. It is much harder to respond to random shots from a robot than from a real person. If we are going to add randomization to our practice, we need to be aware of these issues, and be creative in how we set up the robot.

One obvious possibility is to set up the robot away from the table. This will give us a longer time to watch the ball, read the shot, and decide where to move to make the return. The second possibility is to make the balls far slower than we would expect in a real game. The main purpose here is not to practice our shots (although that would be preferable), but rather to make rapid decisions and move into place as early as possible. (Different robots have different randomization features. The Amicus is particularly good at providing a number of different randomization functions. Users of other robots may need to be creative in what they do.)

Work on a progression of randomization. Start off with placement: choose one shot, and restrict the decision making to deciding where it will land. Then, progress to making a choice between different shots. Eventually, we want to have totally random shots from the robot, requiring quick decisions regarding placement, spin and shot selection. Try not to over anticipate—wait until you are sure of the right decision— make sure you do not have to change your mind.

Firstly, work on random placement of the same shot:

Have balls fall randomly on the right side of the table, initially with the same spin and speed. You play a series of FH shots, and need to move a little to the left or to the right to make the shot.

Have balls fall randomly on the left of the table, with the same spin and speed. You play a series of BH shots by moving left or right as appropriate.

As you improve, continue with random placement, but set the balls to vary spin and speed.

Secondly, work on the cross-over point. As shake-hand players, one important decision we make is to decide between forehand and backhand when the ball comes to our elbow. It is crucial to practice this skill. The key here is on the decision making.

Have the balls fall randomly around the middle of the table—mid left or mid right. Respond with either BH or FH according to where the balls land, then return to the neutral ready position between shots.

Thirdly, we need to randomize the shots we receive. Start with serves, then at the table blocks, slowly moving back to drive or top-spina.

Set up a number of serves, long, or short, left or right. Randomize delivery. Responds as appropriate.

Repeat with sidespin, topspin or backspin serves. Try to read the spin from the ball (Remember, unlike the server’s bat action, the robot will give little hint of the spin on the ball, so make it easier.)

Receive randomized topspin shots, one to each of left, right and mid table. Stand near the table and block each one, returning to the ready position after each shot.

As you get better, move away from the table to take the same random shots, but with a drive or a top-spin.

Fourthly, totally random shots.

Take any of the Stage Three drills, or any other drills, and randomize the whole sequence of shots. Perhaps you will need to slow them down, or place the robot away from the table. Start with easy drills, and slowly increase difficulty. Since the emphasis is on decision-making, make sure you provide yourself enough information to actually make the decision. If you make the random drills too hard (easy to do with a robot), then you will only frustrate yourself. Be creative, and be realistic.

The goal is to be able to respond to any shot, of any type, placed anywhere on the table.

Stage Six: Practice Games and Match Strategy

In Stage Six, the purpose is to take the skills you have learned and integrate them into your game. This is where you need a partner. Play a variety of practice games, try out your skills, and evaluate your performance. Identify any weaknesses you find, and then, if possible, devise robot drills to work on those weakness.

There is clearly a limit to what you can learn from using a robot, and this is where you will find out what those limits are. You should have a wide range of important skills, but you cannot learn tactics from a robot, nor can you learn to deal with the wide variety of players and playing styles. But you should be able to identify gaps in your game, and in many cases, you will be able to use the robot to work on those gaps. If not, then you need a coach.

Good luck.

Copyright Gary Buck, 2017. All rights reserved.

Thoughts on this blog

Gary Buck Posted 1 year ago

I am new to table tennis, and figuring out how to learn such a complex skill is not an easy task. This blog is what I have understood over the last six months. I would love to hear comments and suggestions from more experienced players, or coaches. I am sure that my ideas could be significantly refined by a thorough critical review. If there are significant changes needed, I will revise it, and then share it with the online community.

Gary

Gunnar Östberg Posted 1 year ago

Hi Gary, very well written, I could not have made it better myself ;-) Thanks a lot for sharing!

I am in a similar situation as you are, and in fact, I use the exact same approach, although I am perhaps not as ambitious as you seem to be.

So, I agree with all of this, I just have two minor comments: 1) I would start with a warm-up (for instance, jogging) and get the heart rate up and warm up the whole body BEFORE I do the stretching. This is what I always do myself. Muscles should be warm when doing the stretches, that is what I have been told by all coaches and physiotherapists. 2) It is Falkenberg, not Falkenburg, here is "TheFalconRock" club from which the exercise origins: https://www.google.se/maps/place/Falkenbergs+Bordtennisklubb/@56.9073896,12.4900947,17z/data=!3m1!4b1!4m5!3m4!1s0x4651ce956637b775:0x2171978b37009d91!8m2!3d56.9073867!4d12.4922834

My view on working with the robot is as in this post: https://medium.com/@ttdementor/practicing-with-a-table-tennis-robot-2dd9fbbb6af1

Gunnar Östberg Posted 1 year ago

Parts of the lines disappeared when posting, the form truncated the lines:

It should say

"... and warm up the whole body BEFORE I do the stretching. This iswhat I always do myself. ..."

"2) It is Falkenberg, not Falkenburg. Here is the club from which the exercise origins: " The working maps link is (hopefully) here

Alois Rosario from PingSkills Posted 1 year ago

Thanks for your thoughts, Gunnar. I will check with Jeff as to why it truncated the message.

Jeff Plumb from PingSkills Posted 1 year ago

I'm not really sure why the message is truncated? Again thanks for sharing your thoughts Gunnar.

Gary Buck Posted 1 year ago

Hi Gunnar,

Thanks for the positive response. Sorry about the typo--I'll try to get the right berg in the future. As for the need to warm-up, I appreciate your emphasis on this. Like too many amateur athletes, I don't warm up enough.

The link you sent is very interesting. I have the Amicus Professional, which has all the feature that the writer says he would like. But even then, there is a definite limit to what you can learn with a robot. Much as it helps train many important table tennis skills, it cannot teach you how to play table tennis. Firstly, it is a challenge to transfer skills learned on a robot to real-world play, and secondly, there are a host of other skills that need to be learned. Never-the-less, I do find that the robot is a helpful supplement to working with a coach and playing against real people.

And further, if you incorporate good footwork drills, as one should, I am finding that I can get a really good aerobic workout. I do intervals: a minute of fast footwork drills, 20 seconds rest, then repeat a few times. Then choose another footwork drill, and repeat as needed. You can set the frequency and placement to be as challenging as you wish. Half an hour three times a week is a good basic aerobic fitness regime. I think an hour a day, four or five days a week, would get anyone in decent shape after a few months. Or at least, that is what I am hoping.